JPH0794553B2 - Polyimide oligomer and heat-resistant adhesive containing the oligomer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel polyimide oligomer useful as a heat-resistant adhesive, and a heat-resistant adhesive containing the oligomer.

[Conventional technology]

Heretofore, heat-resistant adhesives made of various organic synthetic polymers have been known. Among them, polybenzimidazole-based and polyimide-based adhesives have been developed as those having excellent heat resistance.

In addition to the above-mentioned adhesives, fluororesins, polyamideimides, silicones, epoxy novolacs, epoxy acrylics, nitrile rubbers, phenols, polyesters, and other adhesives have been developed, but these are satisfactory in terms of heat resistance. Some of them are inadequate in adhesive strength, and on the other hand, those in which adhesive strength is excellent are inferior in heat resistance and are not sufficiently satisfactory.

On the other hand, a polyimide-based adhesive is used as one having excellent heat resistance, for example, a polyimide adhesive developed by DJ Progar et al. (US Patent No. 4,065,345) as one having excellent heat resistance and adhesive strength. As is known, the usual polyimide resin is completely cyclized, and when it is in a polyimide state, it has very poor melt fluidity,
It was difficult to use.

[Problems to be solved by the invention]

The object of the present invention is to provide a novel polyimide oligomer which exhibits a high melt flowability and a strong adhesive when used as an adhesive, and does not deteriorate the adhesive strength during use and after use even when used at high temperature. And to provide a heat resistant adhesive containing the oligomer thereof.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the present inventors have found a novel polyimide oligomer and a heat-resistant adhesive containing the oligomer.

That is, the present invention has the general formula (I) [In the formula, R ₁ is Represents a group selected from the group consisting of, X is --CH _2- , --C
O -, - O -, - S -, - SO 2 -, or a direct bond aromatic rings, R ₂ is Represents Y, —CH ₂ —, And n is 0.5 to 10 on average. ] Another invention of the present invention is a polyimide oligomer represented by the general formula (I) [In the formula, R ₁ is Represents a group selected from the group consisting of, X is --CH _2- , --C
O -, - O -, - S -, - SO 2 -, or a direct bond aromatic rings, R ₂ is Represents Y, —CH ₂ —, And n is 0.5 to 10 on average. ] It is a heat resistant adhesive containing a polyimide oligomer represented by the following.

The polyimide oligomer of the present invention can be obtained by the following method via its polyamic acid oligomer of the formula (II).

[In the formula, R ₁ is Represents a group selected from the group consisting of, X is --CH _2- , --C
O -, - O -, - S -, - SO 2 -, or a direct bond aromatic rings, R ₂ is Represents Y, —CH ₂ —, And n is 0.5 to 10 on average. ].

That is, the polyamic acid oligomer has formula (III) and formula (IV) [In the formula, X is the same as X in the above formulas I and II], and a tetracarboxylic dianhydride selected from the group consisting of [Wherein Y is the same as Y in the above formulas I and II] and a diamine compound selected from the group consisting of maleic anhydride are reacted in an organic solvent.

The polyimide oligomer of the present invention is obtained by heating or chemically dehydrating and imidizing this polyamic acid oligomer.

The terminal maleimide-type polyimide oligomer thus obtained and the terminal maleamic acid-type polyamic acid oligomer of the precursor thereof are novel compounds which have never been known.

Examples of the tetracarboxylic dianhydride used in this method include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and bis (3,4-dicaboxoxyphenyl). ) Ether dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3,4
-Dicarboxyphenyl) sulfone dianhydride, bis (3,
4-dicarboxyphenyl) methane dianhydride and the like, and particularly preferable tetracarboxylic acid dianhydrides are pyromellitic dianhydride and 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride.

These tetracarboxylic dianhydrides may be used alone or
Used as a mixture of two or more species.

The diamine compound used is, for example, 3,3′-diaminodiphenylmethane, 1,3-bis (3-aminophenoxy) benzene, 4,4′-bis (3-aminophenoxy) biphenyl, which are used alone. Alternatively, two or more kinds may be mixed and used.

Other diamine compounds used as a mixture,
3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenyl sulfone, 3,
4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether and 3,
4'-diaminodiphenyl ether and the like can be mentioned.

By using a compound having a diamino group at the 3,3'-position, a polyimide oligomer having excellent melt fluidity and high adhesive strength and its precursor can be obtained. Among them, a particularly preferred diamine compound is 1,3-bis (3-aminophenoxy) benzene. This diamine compound can also be used as a mixture with the above diamine compound within a range that does not impair the excellent performance of the polyimide oligomer obtained using the same.

Any combination of these diamine compounds and tetracarboxylic dianhydrides may be used, but as tetracarboxylic dianhydrides, pyromellitic dianhydride (hereinafter abbreviated as PMDA) and / or 3,3. ′, 4,4 ′
-A polyimide oligomer obtained by combining benzophenone tetracarboxylic dianhydride and 1,3-bis (3-aminophenoxy) benzene (hereinafter abbreviated as APB) as a diamine compound has fluidity, adhesiveness, and heat resistance. Is particularly good.

The molar ratio of each monomer charged in the polyamic acid oligomer formation reaction was as follows: 1.5 mol to 11 mol of diamine compound and 0.5 to 10 mol of tetracarboxylic acid dianhydride to 2 mol of maleic anhydride (hereinafter abbreviated as MAA). It is suitable.

The weight average molecular weight (Mw) of the obtained polyamic acid oligomer is 500 to 10,000, more preferably 800 to 2,50.
It is 0.

When the molecular weight is 10,000 or more, the fluidity is remarkably reduced and the adhesive strength is insufficient.

The reaction for producing the polyamic acid oligomer is usually carried out in an organic solvent. As the organic solvent used in this reaction, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis {2- (2-methoxyethoxy)
Ethyl} ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea, hexamethylphosphoramide and the like can be mentioned. These organic solvents may be used alone or in combination of two or more.

The reaction temperature is usually 60 ° C or lower, preferably 50 ° C or lower.

The reaction pressure is not particularly limited and can be carried out at normal pressure.

The reaction time varies depending on the type of tetracarboxylic dianhydride, diamine compound, solvent used and the reaction temperature, but it is a time sufficient for forming a polyamic acid oligomer, and usually 4 to 24 hours.

By such a reaction, a polyamic acid oligomer represented by the following formula (II) is obtained.

[In the formula, R ₁ , R ₂ and n are as described above. The polyimide represented by the following formula (I) can be easily prepared by a thermal imidization method in which the resulting polyamic acid oligomer is dehydrated by heating at 100 to 300 ° C. for imidization, or a chemical imidization method using a dehydration imidizing agent. An oligomer is obtained.

[In the formula, R ₁ , R ₂ and n are as described above. The average number of polymerizations n of the polyamic acid oligomer and the polyimide oligomer of the present invention is 0.5 to 10 on average, and preferably 1 to 4. Average polymerization number n is 0.5
If it does not satisfy, the melt fluidity is good when used as an adhesive, but satisfactory adhesive strength cannot be obtained, and especially the adhesive strength at high temperature is significantly reduced. On the other hand, when n exceeds 10, the melt fluidity is significantly impaired and the adhesive strength is low.

The thermal imidization method is a method of heating the obtained polyamic acid oligomer or heating and dehydrating the solution at 100 to 300 ° C. for 30 minutes to 6 hours to complete the imidization.

The chemical imidization method is a method of adding a dehydration imidizing agent to a polyamic acid oligomer or a solution thereof. As the dehydration imidizing agent, one or a mixture of two or more selected from acetic anhydride, propionic anhydride, isobutyric anhydride and butyric anhydride is used.

The dehydration imidizing agent may be added directly to the polyamic acid oligomer or may be diluted with an organic solvent and added. As the organic solvent, any of the above-mentioned organic solvents that can be used in the reaction for producing a polyamic acid oligomer can be used.

The amount of the dehydration imidizing agent to be added is 0.8 to 4 equivalents, particularly preferably 1 to 2 equivalents based on the carboxyl groups present in the polyamic acid oligomer.

It is also possible to add an imidization catalyst at the same time, and examples of the catalyst include tertiary amines such as trimethylamine, triethylamine, tributylamine, pyridine, α-picoline, β-picoline, γ-picoline and lutidine. To be

When a catalyst is used, it is used in an amount of 0.05 to 1.5 equivalents, preferably 0.2 to 1 equivalents, based on the carboxyl groups present in the polyamic acid.

The weight average molecular weight (Mw) of the obtained polyimide oligomer is also 500 to 10,000, and more preferably 800 to 10,000.
It is 2,500.

When the molecular weight is 10,000 or more, the fluidity is remarkably reduced and the adhesive strength is insufficient.

The adhesive of the present invention contains the polyimide oligomer thus obtained, and can be used as a heat resistant adhesive in the following modes.

For example, a polyamic acid oligomer precursor is heated and dehydrated to form a film, or is heated or chemically imidized to be powdered, and a part of the polyamic acid oligomer may be contained.

When such a polyimide oligomer is used, a film is inserted between the adherends, or powder is applied to the adherends by a conventional method, and one of the adherends is overlaid to
Pressure of ~1,000kg / cm ^2, and pressed at a temperature of 50 to 400 ° C., 100
When cured at a temperature of ~ 400 ° C, the adhesive substance can be firmly bonded.

The polyamic acid oligomer which is a precursor of the polyimide oligomer of the present invention can also be used as the heat resistant adhesive. In this case, the polyamic acid oligomer is used as a solution prepared by dissolving it in an organic solvent. The reaction solution obtained by reacting a tetracarboxylic dianhydride, a diamine compound and MAA in an organic solvent may be as it is, or may be one in which a partially imidized polyimide oligomer is dissolved. It may be present, or may be a solution in which a polyimide oligomer is partially suspended.

The obtained adhesive solution preferably contains a resin content of 20 to 60% by weight, from the viewpoint of easy handling of the solution and adhesive strength, and particularly preferably 30 to 50% by weight.

When using a solution containing such a polyamic acid oligomer, apply a thin film of the polyamic acid oligomer solution to the adherends to be laminated, and then in air
Preheat to about 220 ℃ to remove excess solvent, convert the polyamic acid oligomer to a more stable polyimide oligomer, overlay this with another adherend, then 1 to 1,000 kg / cm
^By press-bonding at a pressure of ² at a temperature of 50 to 400 ° C. and curing at a temperature of 100 to 400 ° C., the adherend can be firmly bonded.

〔Example〕

 The present invention will be specifically described with reference to Examples and Comparative Examples.

Example-1 (a) Preparation of Polyamic Acid Oligomer 150 ml of N, N-dimethylacetamide in a 500 ml four-necked flask.
5g, APB58.4g (0.20mol) was put in, and while stirring under a dry nitrogen stream at 15 ° C, 27.3g (0.13mol) of PMDA powder and 14.7g (0.15mol) of MAA powder were alternately divided into 5 parts. Was added. The viscosity of the solution increases with the addition. After the addition was completed, the reaction was further stirred for 4 hours to complete the reaction. The obtained polyamic acid oligomer solution was light brown and transparent. A part of the resulting polyamic acid oligomer solution was dropped into water, and the molecular weight (polystyrene molecular weight conversion value) of the precipitated polyamic acid oligomer powder was measured. As a result, the weight average molecular weight (Mw) was 620 and the number average molecular weight (Mn) was Was 996 and the average number of polymerizations (n) was 1.7. The infrared absorption spectrum of the obtained polyamic acid oligomer powder is shown in FIG.

(B) Imidization In 40 g of the polyamic acid oligomer solution obtained in (a),
20 ml of triene was added, refluxed for 6 hours, and water was collected with a Dean Stark receiver. When the solution was cooled to room temperature, a pale yellow polyimide oligomer was precipitated. The polyimide oligomer was filtered, washed with water and methanol, and dried under reduced pressure at 120 ° C. to obtain 14.2 g of the polyimide oligomer. This polyimide oligomer is a pale yellow powder and has a 5% heat loss temperature of 41
It was 4 ° C. The infrared absorption spectrum of the obtained polyimide oligomer powder is shown in FIG.

(C) Adhesion test The polyimide oligomer obtained in (b) was applied to a cold-rolled steel sheet (JIS G-3141, SPCC, SD, size 1.6 x 25 x 10 mm; the same applies below), and another cold-rolled steel sheet was applied. And was heat-pressed at 330 ° C. and 3.5 kg / cm ² for 30 minutes. The tensile shear adhesive strength was 318 kg / cm ² at room temperature. (Measurement method is JIS
According to K-6848 and K-6850. The same applies below. This was further measured at a high temperature of 200 ° C. and found to be 203 kg / cm ² .

Example-2 (a) Production of polyamic acid oligomer and imidization
Polymerization was carried out under the same conditions as in Example-1 (a), and the resin component was
A 40% by weight light brown transparent polyamic acid oligomer solution was obtained. 20 g of the obtained polyamic acid oligomer solution was N, N-
After adding 20 g of dimethylacetamide, 45.9 g (0.45 mol) of acetic anhydride while stirring under a stream of dry nitrogen at 20 ° C,
8.1 g (0.08 mol) of triethylamine was added dropwise. After stirring for 6 hours after the completion of dropping, a pale yellow polyimide oligomer was deposited. This was filtered, washed with water and methanol, and dried under reduced pressure at 120 ° C. The obtained polyimide oligomer was a pale yellow powder and had a 5% loss on temperature of 468 ° C.

(B) Adhesion test The polyimide oligomer obtained in (a) was applied to a cold-rolled steel sheet, and was superposed on another cold-rolled steel sheet and then hot-pressed 330
° C., was bonded with 3.5kg / cm ^2, 30 minutes. The tensile shear bond strength was 285 kg / cm ² at room temperature. When this was further measured at a high temperature of 200 ° C., it was 155 kg / cm ² .

Comparative Example-1 (a) Production of Polyamic Acid Oligomer N, N-dimethylacetamide 165.
5g, APB58.4g (0.20mol), 15 ℃, while stirring under a stream of dry nitrogen, PMDA powder 27.3g (0.13mol) and nadic acid anhydride powder 24.6g (0.15mol) alternately 5 times alternately. Was added separately. The viscosity of the solution increases with the addition. After the addition was completed, stirring was continued for another 4 hours to complete the reaction. The obtained polyamic acid oligomer solution was light brown and transparent. A part of the obtained polyamic acid oligomer solution was dropped into water, and the molecular weight of the precipitated polyamic acid oligomer powder was measured. As a result, the weight average molecular weight (Mw) was
1,780, the number average molecular weight (Mn) is 910, and the average polymerization number (n) is
It was 1.7.

(B) Imidization The polyamic acid oligomer solution obtained in (a) was imidized under the same conditions in Example-1 (b) to obtain a pale yellow polyimide oligomer powder. The 5% weight loss temperature was 342 ° C.

(C) Adhesion test The polyimide oligomer obtained in (b) was used as Example-1.
An adhesion test was conducted under the same conditions as in (c). The tensile shear strength was 100 kg / cm ² at room temperature. When this was further measured at a high temperature of 200 ° C., it was 25 kg / cm ² .

Examples 3 to 10 and Comparative Examples 2 to 8 Polymerization was carried out in the same manner as in Example-1 (a) using various tetracarboxylic acid dianhydrides and diamine compounds, and the same as in Example-1 (b). Imidization was carried out by the method described above to obtain a polyimide oligomer. An adhesion test was conducted using this polyimide oligomer, and the results shown in Tables 1 and 2 were obtained.

[Advantages of the Invention] The present invention comprises a novel polyimide oligomer and oligomer useful as an adhesive exhibiting a strong adhesive force without lowering the heat resistance and maintaining a high adhesive force even at a high temperature. A heat resistant adhesive is provided.

[Brief description of drawings]

FIG. 1 is an example of an infrared absorption spectrum of the polyamic acid oligomer powder of the present invention, and FIG. 2 is an example of an infrared absorption spectrum of the polyimide oligomer powder.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C09J 179/08 JGE // (C07D 519/00 209: 00)

Claims (2)

[Claims] 1. A general formula (I) [In the formula, R ₁ is Represents a group selected from the group consisting of, X is --CH _2- , --C
O -, - O -, - S -, - SO 2 -, or a direct bond aromatic rings, R ₂ is Represents Y, —CH ₂ —, And n is 0.5 to 10 on average. ] The polyimide oligomer represented by these. 2. General formula (I) [In the formula, R ₁ is Represents a group selected from the group consisting of, X is --CH _2- , --C
O -, - O -, - O -, - S -, - SO 2 -, or a direct bond aromatic rings, R ₂ is Represents Y, —CH ₂ —, And n is 0.5 to 10 on average. ] A heat-resistant adhesive containing a polyimide oligomer represented by the following.